NEW YORK — A former employee of Rabobank on Monday became the second of the Dutch bank's ex-traders to plead guilty in a criminal plot to manipulate a global financial benchmark used to set rates on trillions of dollars in loans.

United Kingdom citizen Paul Robson, pleaded guilty to conspiracy in Manhattan federal court, admitting he helped manipulate the London Interbank Offered Rate for Japanese yen between May 2006 and January 2011 in a plot to boost trading profits for himself and others.

Widely known as Libor, the benchmark represents the rates that London-based global banks would expect to pay in exchange for loans from each other in a variety of world currencies for different lengths of time.

Authorities in the U.S. and around the world have been pursuing a multi-year investigation of evidence that bank traders regularly rigged Libor, which is used to set rates on mortgages, credit cards, many types of loans and some financial derivatives.

"The scope of the fraud was massive, but the scheme was simple," said Assistant Attorney General Leslie Caldwell of the Department of Justice's criminal division. "By illegally influencing the Libor rates, Robson and his co-conspirators rigged the markets to ensure that their trades made money."

Robson admitted guilt two months after Takayuki Yagami, another former Rabobank trader targeted in the case, pleaded guilty to one count of conspiracy to commit wire and bank fraud for his involvement.

Utrecht-based Rabobank itself was fined nearly $1.1 billion by authorities in the U.S. and Europe last year to resolve Libor-related violations.

Robson entered his guilty plea to an April 2014 indictment in a hearing before U.S. District Court Judge Jed Rakoff. The judge ordered the former bank trader to post a $500,000 personal recognizance bond secured by $90,000 cash in order to return to the United Kingdom. Rakoff also set a June 2017 sentencing date.

Court records show Robson was Rabobank's primary submitter of Japanese yen Libor rates to the British Bankers' Association, which oversaw the financial benchmark. His main role in the conspiracy was submitting rates at the requests of traders who had derivatives contracts that included Libor as a component.

Robson admitted he accommodated other traders by submitting artificially high or low Libor rates of Japanese yen. In one incident cited in court records, Rabobank submitted a one-month yen Libor rate of 0.90 on Sept. 21, 2007 at Yagami's request. That rate was seven basis points higher than the previous day and five basis points above the level Robson said that "bookies' predicted it, investigators alleged.

At times, Robson allegedly referred to his Japanese yen Libor submissions as "ridiculously high" or "obscenely high," and speculated that the British Bankers' Association might contact him about them.